Headlight aiming

[Mike H.]

I'm putting this under the Mods page because it will be different with a lifted crew than stock. Anybody got any guidelines as to headlight aiming? I.e. how far to park away from the wall, height and width of beam center points on the wall, etc. Is there a factory spec on headlight aiming? It should all be similar for folks with the BL & Daystars, depending on the T-bar setting. Has anybody found a sweet spot?

[HenryJ]

I'll see if I can find that information again. I had a website that gave a "layman's" method for aiming headlights.

[Mike H.]

I can do trial and error, but was wondering if there was an "official" setting. Mine seem to be a little high and a little close together.

[HenryJ]

I didn't have the information that I thought I had (Must be CRS setting in )
I did throw together a webpage for the Mod Info Page : Aiming Lights
It may be of some help, I'll check into the specs for the stock lights as time permits.
Or maybe someone else will find the information, first?

EDIT: Here is a link to the Federal Statues : 49cfr571.108.pdf

(a) Vertical aim, lower beam. Each
lower beam headlamp shall have a cutoff
in the beam pattern. It may be either
on the left side or the right side of
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49 CFR Ch. V (10–1–03 Edition) § 571.108
the optical axis, but once chosen for a
particular headlamp system’s design,
the side chosen for the cutoff shall not
be changed for any headlamps intended
to be used as replacements for those
system’s headlamps.
(1) Vertical position of cutoff. The
headlamp shall be aimed vertically so
that the cutoff is on the left side, at 0.4
degree down from the H–H line, or on
the right side, at the H–H line.
(2) Vertical gradient. The gradient of
the cutoff measured at either 2.5 degrees
L or 2.0 degrees R shall be not
less than 0.13 based on the procedure of
S7.8.5.3, paragraph (a)(5).
(3) Horizontal position of the cutoff.
The width shall be not less than two
degrees, with not less than two degrees
of its actual width centered at either
2.5 degrees L, or 2.0 degrees R.
(4) Maximum inclination of cutoff. The
vertical location of the highest gradient
at the ends of the minimum
width shall be within ±0.2 degree of the
vertical location of the maximum gradient
measured at the appropriate
vertical line (at either 2.5 degrees L for
a left side cutoff, or 2.0 degrees R for a
right side cutoff.)
(5) Measuring the cutoff parameter. (i)
The headlamp shall be mounted on a
fixture which simulates its actual design
location on any vehicle for which
the headlamp is intended. The fixture,
with the headlamp installed shall be
attached to the goniometer table in
such a way that the fixture alignment
axes are coincident with the goniometer
axes. The headlamp shall be energized
at the specified test voltage.
(ii) The headlamp beam pattern shall
be aimed with the cutoff at the H-H
axis. There shall be no adjustment,
shimming, or modification of the horizontal
axis of the headlamp or test fixture,
unless the headlamp is equipped
with a VHAD. In this case the VHAD
shall be adjusted to zero.
(iii) A vertical scan of the beam pattern
shall be conducted for a headlamp
with a left side gradient by aligning
the goniometer on a vertical line at 2.5
degrees L and scanning from 1.5 degrees
U to 1.5 degrees D. For a
headlamp with a right side gradient, a
vertical scan of the beam pattern shall
be conducted by aligning the goniometer
on a vertical line at 2.0 degrees R
and scanning from 1.5 degrees U to 1.5
degrees D.
(iv) Determine the maximum gradient
within the range of the scan by
using the formula: G = log E(a)-log
E(a+0.1), where ‘‘G’’ is the gradient,
‘‘E’’ is illumination and ‘‘a’’ is vertical
angular position. The maximum value
of the gradient ‘‘G’’ determines the
vertical angular location of the cutoff.
Perform vertical scans at 1.0 degree L
and R of the measurement point of the
maximum gradient to determine the
inclination.
(b) Horizontal aim, lower beam. There
shall be no adjustment of horizontal
aim unless the headlamp is equipped
with a horizontal VHAD. If the
headlamp has a VHAD, it shall be set
to zero.
(c) Vertical aim, upper beam. (1) If the
upper beam is combined in a headlamp
with a lower beam, the vertical aim of
the upper beam shall not be changed
from the aim set using the procedures
of paragraphs S7.8.5.3(a) and (b) used
for the lower beam.
(2) If the upper beam is not combined
in a headlamp with a lower beam, the
vertical aim of the upper beam shall be
adjusted so that the maximum beam
intensity is located on the H-H axis.
(d) Horizontal aim, upper beam. (1) If
the upper beam is combined in a
headlamp with a lower beam, the horizontal
aim of the upper beam shall not
be changed from the aim set using the
procedures of paragraphs S7.8.5.3 (a)
and (b) used for the lower beam.
(2) If the upper beam is not combined
in a headlamp with the lower beam and
has fixed horizontal aim or has a horizontal
VHAD, then the headlamp shall
be mounted on a fixture which simulates
its actual design location on any
vehicle for which the headlamp is intended.
The fixture, with the headlamp
installed shall be attached to the goniometer
table in such a way that the
fixture alignment axes are coincident
with the goniometer axes. The
headlamp shall be energized at 12.8
±0.20 mV. There shall be no adjustment,
shimming, or modification of the
horizontal axis of the headlamp or test
fixture, unless the headlamp is
equipped with a VHAD. In this case the
VHAD shall be adjusted to zero.

Guess a headlight aiming tool would be the best option

[Mike H.]

I didn't have the information that I thought I had (Must be CRS setting in )
I did throw together a webpage for the Mod Info Page : Aiming Lights
It may be of some help.

Cool. 1.5" low at 25' might be a little hard to measure the center of the spot, but 3/4" low at 12.5' should create the same end result. Is there a guideline on width?

I don't seem to have one of those "goniometer table" things they mention. Are "goniometer axes" used to chop down big trees? Typical government language.

[HenryJ]

Here is a helpful webpage with instructions- Headlight aiming